NSString 和NSArray用法大全
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1、NSString
建立字符串。
NSString *astring = @"This is a String!";
建立空字符串，給予賦值。
NSString *astring = [[NSString alloc] init];
astring = @"This is a String!";
NSLog(@"astring:%@",astring);
string release];
使用變量初始化
NSString *name = @"Ivan!";
NSString *astring = [[NSString stringWithFormat:@」My name is %@!」,name]];
NSLog(@"astring:%@",astring);
判斷是否包含某字符串
檢查字符串是否以另外一個字符串開頭
- (BOOL) hasPrefix: (NSString *) aString;
NSString *String1 = @"NSStringInformation.txt";
[String1 hasPrefix:@"NSString"] == 1 ? NSLog(@"YES") : NSLog(@"NO");
[String1 hasSuffix:@".txt"] == 1 ? NSLog(@"YES") : NSLog(@"NO");
是否包含其它字符
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
Boolean contains = [astring rangeOfString:@」This」].length>0;
從文件讀取字符串:
initWithContentsOfFile方法
NSString *path = @"astring.text";
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];
寫字符串到文件:writeToFile方法
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
NSString *path = @"astring.text";
[astring writeToFile: path atomically: YES];
[astring release];
比較兩個字符串
isEqualToString方法
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);
compare方法(comparer返回的三種值)
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
NSOrderedSame判斷二者內容是否相同
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"this is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
NSLog(@"result:%d",result);
不考慮大小寫比較字符串1
NSString *astring01 = @"this is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
改變字符串的大小寫
NSString *string1 = @"A String";
NSString *string2 = @"String";
NSLog(@"string1:%@",[string1 uppercaseString]);//大寫
NSLog(@"string2:%@",[string2 lowercaseString]);//小寫
NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小
在串中搜索子串
NSString *string1 = @"This is a string";
NSString *string2 = @"string";
NSRange range = [string1 rangeOfString:string2];
int location = range.location;
int leight = range.length;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@"astring:%@",astring);
[astring release];
替換字符串
NSString *astring01 = @"hello 中國";
NSString * new = [astring01 stringByReplacingOccurrencesOfString:@」中國」 withString:@"北京"];
NSLog(new);
分割字符串成數組
NSString *s = @"a b d e f";
NSArray *arr = [s componentsSeparatedByString:@" "];
NSLog(@"count = %d",[arr count]);
字符串數組拼接成字符串
NSArray *pathArray = [NSArray arrayWithObjects:@"here",
@"be", @"dragons", nil];
NSLog(@"%@",[pathArray componentsJoinedByString:@""]);
抽取子串
-substringToIndex: 從字符串的開頭一直截取到指定的位置，但不包括該位置的字符
NSString *string1 = @"This is a string";
NSString *string2 = [string1 substringToIndex:3];
NSLog(@"string2:%@",string2);
-substringFromIndex: 以指定位置開始（包括指定位置的字符），幷包括以後的所有字符
NSString *string1 = @"This is a string";
NSString *string2 = [string1 substringFromIndex:3];
NSLog(@"string2:%@",string2);
-substringWithRange: //按照所給出的位置，長度，任意地從字符串中截取子串
NSString *string1 = @"This is a string";
NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
NSLog(@"string2:%@",string2);
2、NSMutableString
給字符串分配容量
//stringWithCapacity:
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];
在已有字符串後面添加字符
//appendString: and appendFormat:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
//[String1 appendString:@", I will be adding some character"];
[String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
NSLog(@"String1:%@",String1);
*/
在已有字符串中按照所給出範圍和長度刪除字符
//deleteCharactersInRange:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog(@"String1:%@",String1);
在已有字符串後面在所指定的位置中插入給出的字符串
//-insertString: atIndex:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
NSLog(@"String1:%@",String1);
將已有的換成其它的字符串
//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);
按照所給出的範圍，和字符串替換的原有的字符
//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
NSLog(@"String1:%@",String1);
3、NSArray
建立數組
NSArray *array = [[NSArray alloc] initWithObjects:
@"One",@"Two",@"Three",@"Four",nil];
self.dataArray = array;
[array release];
//- (unsigned) Count;數組所包含對象個數；
NSLog(@"self.dataArray cound:%d",[self.dataArray count]);
//獲取指定索引處的對象
NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);
從一個數組拷貝數據到另外一數組
//arrayWithArray:
//NSArray *array1 = [[NSArray alloc] init];
NSMutableArray *MutableArray = [[NSMutableArray alloc] init];
NSArray *array = [NSArray arrayWithObjects:
@"a",@"b",@"c",nil];
NSLog(@"array:%@",array);
MutableArray = [NSMutableArray arrayWithArray:array];
NSLog(@"MutableArray:%@",MutableArray);
array1 = [NSArray arrayWithArray:array];
NSLog(@"array1:%@",array1);
//Copy
//id obj;
NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
for(int i = 0; i < [oldArray count]; i++)
{
obj = [[oldArray objectAtIndex:i] copy];
[newArray addObject: obj];
}
//
NSLog(@"newArray:%@", newArray);
[newArray release];
快速遍歷數組
//NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
for(id obj in oldArray)
{
[newArray addObject: obj];
}
//
NSLog(@"newArray:%@", newArray);
[newArray release];
Copy and sort
//NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:
@"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];
NSLog(@"oldArray:%@",oldArray);
NSEnumerator *enumerator;
enumerator = [oldArray objectEnumerator];
id obj;
while(obj = [enumerator nextObject])
{
[newArray addObject: obj];
}
[newArray sortUsingSelector:@selector(compare:)];
NSLog(@"newArray:%@", newArray);
[newArray release];
NSMutableArray
給數組分配容量
//NSArray *array;
array = [NSMutableArray arrayWithCapacity:20];
在數組末尾添加對象
//- (void) addObject: (id) anObject;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array addObject:@"Four"];
NSLog(@"array:%@",array);
刪除數組中指定索引處對象
//-(void) removeObjectAtIndex: (unsigned) index;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array removeObjectAtIndex:1];
NSLog(@"array:%@",array);
數組枚舉
從前向後
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array objectEnumerator];
id thingie;
while (thingie = [enumerator nextObject]) {
NSLog(@"thingie:%@",thingie);
}
從後向前
NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array reverseObjectEnumerator];
id object;
while (object = [enumerator nextObject]) {
NSLog(@"object:%@",object);
}
快速枚舉
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
for(NSString *string in array)
{
NSLog(@"string:%@",string);
}
NSDictionary
建立字典
//- (id) initWithObjectsAndKeys;
ctionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
NSString *string = [dictionary objectForKey:@"One"];
NSLog(@"string:%@",string);
NSLog(@"dictionary:%@",dictionary);
[dictionary release];
練習題：將文本「成績單.text」內容加載到內存中並按規定的格式輸出出來
NSMutableDictionary
建立
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
添加字典
[dictionary setObject:@"One" forKey:@"1"];
[dictionary setObject:@"Two" forKey:@"2"];
[dictionary setObject:@"Three" forKey:@"3"];
[dictionary setObject:@"Four" forKey:@"4"];
NSLog(@"dictionary:%@",dictionary);
刪除指定的字典
[dictionary removeObjectForKey:@"3"];
NSLog(@"dictionary:%@",dictionary);
NSValue（對任何對象進行包裝）
將NSRect放入NSArray中
NSMutableArray *array = [[NSMutableArray alloc] init];
NSValue *value;
CGRect rect = CGRectMake(0, 0, 320, 480);
value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)];
[array addObject:value];
NSLog(@"array:%@",array);
從Array中提取
value = [array objectAtIndex:0];
[value getValue:&rect];
NSLog(@"value:%@",value);
定義結構體並添加到NSArray裏面
typedef struct {
float real;
float imaginary;
} ImaginaryNumber;
ImaginaryNumber miNumber;
miNumber.real = 1.1;
miNumber.imaginary = 1.41;
NSValue *miValue = [NSValue value:miNumber
withObjCType:@encode(ImaginaryNumber)]; // encode using the type name
ImaginaryNumber miNumber2;
[miValue getValue:&miNumber2];
4、宏定義#define講解
NSNumber
+ (NSNumber *)numberWithInt:(int)value;
+ (NSNumber *)numberWithDouble:(double)value;
- (int)intValue;
- (double)doubleValue;
NSNumber能夠將基本數據類型包裝起來，造成一個對象，這樣就能夠給其發送消息，裝入NSArray中等等。
NSNumber * intNumber=[NSNumber numberWithInt：100]；
NSNumber *floatNumber=[NSNUmber numberWithFloat:100.00];
int i=[intNumber intValue]；
if([intNumber isEqualToNumber:floatNumber]) ....
NSNumber繼承NSObject ，能夠使用比較 compare： isEqual等消息
NSNull
IOS裏面最小簡單的類，裏面只有一個方法+(NSNull*) null;
數學經常使用方法
數學常量：
#define M_E 2.71828182845904523536028747135266250 // e
#define M_LOG2E 1.44269504088896340735992468100189214 // log 2e
#define M_LOG10E 0.434294481903251827651128918916605082 // log 10e
#define M_LN2 0.693147180559945309417232121458176568 // log e2
#define M_LN10 2.30258509299404568401799145468436421 // log e10
#define M_PI 3.14159265358979323846264338327950288 // pi
#define M_PI_2 1.57079632679489661923132169163975144 // pi/2
#define M_PI_4 0.785398163397448309615660845819875721 // pi/4
#define M_1_PI 0.318309886183790671537767526745028724 // 1/pi
#define M_2_PI 0.636619772367581343075535053490057448 // 2/pi
#define M_2_SQRTPI 1.12837916709551257389615890312154517 // 2/sqrt(pi)
#define M_SQRT2 1.41421356237309504880168872420969808 // sqrt(2)
#define M_SQRT1_2 0.707106781186547524400844362104849039 // 1/sqrt(2)
經常使用函數：
指數運算
NSLog(@"%.f", pow(3,2) ); //result 9
NSLog(@"%.f", pow(3,3) ); //result 27
開平方運算（計算兩點間的距離時用到）
NSLog(@"%.f", sqrt(16) ); //result 4
NSLog(@"%.f", sqrt(81) ); //result 9
上舍入
NSLog(@"res: %.f", ceil(3.000000000001)); //result 4
NSLog(@"res: %.f", ceil(3.00)); //result 3
下舍入
NSLog(@"res: %.f", floor(3.000000000001)); //result 3
NSLog(@"res: %.f", floor(3.9999999)); //result 3
四捨五入
NSLog(@"res: %.f", round(3.5)); //result 4
NSLog(@"res: %.f", round(3.46)); //result 3
NSLog(@"res: %.f", round(-3.5)); //NB: this one returns -4
最小值
NSLog(@"res: %.f", fmin(5,10)); //result 5
最大值
NSLog(@"res: %.f", fmax(5,10)); //result 10
絕對值
NSLog(@"res: %.f", fabs(10)); //result 10
NSLog(@"res: %.f", fabs(-10)); //result 10
NSDate
獲得當前的日期
NSDate *date = [NSDate date];
日期之間比較可用如下方法
- (BOOL)isEqualToDate:(NSDate *)otherDate;// 與otherDate比較，相同返回YES
- (NSDate *)earlierDate:(NSDate *)anotherDate;// 與anotherDate比較，返回較早的那個日期
- (NSDate *)laterDate:(NSDate *)anotherDate;//與anotherDate比較，返回較晚的那個日期
將日期轉換成字符串
NSLog(@」date = %@」,[data description]);
設置日期顯示格式
NSDateFormatter *formatter =[[[NSDateFormatter alloc] init] autorelease];
[formatter setTimeStyle:NSDateFormatterFullStyle]; //設置幾種默認的顯示效果
[formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss a"];//設置自定義的顯示效果
NSLog([formatter stringFromDate:date]);
NSData
NSData－> NSString
NSString *aString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSString－>NSData
NSString *aString = @"1234abcd";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];
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